The oxide of iron that forms on the surface of steel after
Ferrous (iron-containing) material that generally is remelted
and recast into new steel. Integrated steel mills use scrap
for up to 25% of their basic oxygen furnace charge; 100% of
the mini-mills' raw material for their electric furnaces generally
HOME SCRAP Waste steel that is
generated from within the steel mill, through edge trimming
and rejects. It normally is sent directly back to the furnace.
PROMPT (INDUSTRIAL) SCRAP Excess
steel that is trimmed by the auto and appliance stampers and
auctioned to scrap buyers as factory bundles. This is a high-quality
scrap as the result of its low-residual content and consistent
OBSOLETE SCRAP Iron-bearing trash.
Automobile hulks, worn-out refrigerators and useless storage
tanks, for example, can be recovered from the junkyard and
remelted. The residual impurity of such scrap normally relegates
obsolete scrap to the mini-mills (see No.
1 Heavy Melt ).
Raw material that can be charged in place of scrap in electric
arc furnaces and basic oxygen furnaces. Scrap substitutes
include, among others, DRI, HBI, iron carbide, and pig iron.
Pipe made from a solid billet, which is heated, then rotated
under extreme pressure. This rotational pressure creates an
opening in the center of the billet, which is then shaped
by a mandrel to form pipe.
Steel that does not meet the original customer's specifications
because of a defect in its chemistry, gauge or surface quality.
Mills must search to find another customer (that can accept
the lower quality) to take the off-spec steel at a discount.
While secondary will not affect the reported yield, margins
Steel shapes-for example, blooms, billets or slabs-that later
are rolled into finished products such as beams, bars or sheet.
Sendzimir Mill (Z-mill) WHAT Compact mill used for rolling
cold coils of stainless steel in order to make the steel thinner,
smoother, and stronger.
WHY To control the thickness
of steel better at lower capital cost, and to roll thinner
sheets and strips.
HOW Stainless steel sheet or
strip passes between a matching pair of small work rolls with
extremely smooth surfaces, heavily reinforced by clusters
of back-up rolls. The rolls reduce the steel to the desired
thickness. Service Center A catchall name for an operation
that buys steel, often processes it in some way and then sells
it in a slightly different form. A service center is distinguished
from an end-user by the fact that, unlike an end-user, a service
center sells steel, not a fabricated product. Service centers
are manufacturers to the extent that they add labor to steel
by providing a service.
Rolling, heating and quenching steel sheets often affect the
dimensions of the steel. Levelers, temper mills and edge trimmers
rework the processed steel to match customer specifications.
If the edges of sheet and strip are not controlled during
reduction, they must be trimmed parallel by shears. This process
may be performed by either the steel mill or steel processor
to match customer needs.
Thin, flat-rolled steel. Coiled sheet steel accounts for nearly
one-half of all steel shipped domestically and is created
in a hot-strip mill by rolling a cast slab flat while maintaining
the side dimensions. The malleable steel lengthens to several
hundred feet as it is squeezed by the rolling mill. The most
common differences among steel bars, strip, plate, and sheet
are merely their physical dimensions of width and gauge (thickness).
Fist-sized, homogenous pieces of old automobile hulks. After
cars are sent through a shredder, the recyclable steel is
separated by magnets. Mini-mills consume shredded scrap in
their electric arc furnace operations.
Silicon Electrical Steel
A type of specialty steel created by introducing silicon during
the steelmaking process. Electrical steel exhibits certain
magnetic properties, which make it optimum for use in transformers,
power generators and electric motors.
GRAIN-ORIENTED The metal's grain
runs parallel within the steel, permitting easy magnetization
along the length of the steel. Although grain-oriented steel
may be twice as expensive to produce, its magnetic directional
characteristics enable power transformers, made from this
metal, to absorb less energy during operation.
NON-GRAIN-ORIENTED Because there
is no preferential direction for magnetization, non-grain-oriented
steel is best used in rotating apparatus such as electric
A process that combines iron-bearing particles, once recovered
from environmental control filters, into small pellets. Previously,
these materials were too fine to withstand the air currents
of the smelting process and were thrown away. The iron is
now conserved because the chunks can be charged into the blast
furnace (see Agglomerating Processes).
Steel that is the entry material to a pipe mill. It resembles
hot-rolled strip, but its properties allow for the severe
forming and welding operations required for pipe production.
The most common type of semi-finished steel. Traditional slabs
measure 10 inches thick and 30-85 inches wide (and average
about 20 feet long), while the output of the recently developed
"thin slab" casters is approximately two inches thick. Subsequent
to casting, slabs are sent to the hot-strip mill to be rolled
into coiled sheet and plate products.
The impurities in a molten pool of iron. Flux such as limestone
may be added to foster the congregation of undesired elements
into a slag. Because slag is lighter than iron, it will float
on top of the pool, where it can be skimmed.
Cutting a sheet of steel into narrower strips to match customer
needs. Because steel mills have limited flexibility as to
the widths of the sheet that they produce, service centers
normally will cut the sheet for the customer.
Special Bar Quality (SBQ)
SBQ represents a wide variety of higher-quality carbon and
alloy bars that are used in the forging, machining and cold-drawing
industries for the production of automotive parts, hand tools,
electric motor shafts and valves. SBQ generally contains more
alloys than merchant quality and commodity grades of steel
bars, and is produced with more precise dimensions and chemistry.
Category of steel that includes electrical (see Silicon Electrical
Steel), alloy (see Alloy Steel ),
stainless (see Stainless Steel) and tool (see Tool Steels)
Refers to a wide variety of high-quality custom-made tubular
products requiring critical tolerances, precise dimensional
control and special metallurgical properties. Specialty tubing
is used in the manufacture of automotive, construction and
agricultural equipment, and in industrial applications such
as hydraulic cylinders, machine parts and printing rollers.
Because of the range of industrial applications, the market
typically follows general economic conditions.
Sales for delivery in less than three months.
The term for grades of steel that contain more than 10% chromium,
with or without other alloying elements. Stainless steel resists
corrosion, maintains its strength at high temperatures, and
is easily maintained. For these reasons, it is used widely
in items such as automotive and food processing products,
as well as medical and health equipment. The most common grades
of stainless steel are:
TYPE 304 The most commonly specified
austenitic (chromium-nickel stainless class) stainless steel,
accounting for more than half of the stainless steel produced
in the world. This grade withstands ordinary corrosion in
architecture, is durable in typical food processing environments,
and resists most chemicals. Type 304 is available in virtually
all product forms and finishes.
TYPE 316 Austenitic (chromium-nickel
stainless class) stainless steel containing 2%-3% molybdenum
(whereas 304 has none). The inclusion of molybdenum gives
316 greater resistance to various forms of deterioration.
TYPE 409 Ferritic (plain chromium
stainless category) stainless steel suitable for high temperatures.
This grade has the lowest chromium content of all stainless
steels and thus is the least expensive.
TYPE 410 The most widely used
martensitic (plain chromium stainless class with exceptional
strength) stainless steel, featuring the high level of strength
conferred by the martensitics. It is a low-cost, heat-treatable
grade suitable for non-severe corrosion applications.
TYPE 430 The most widely used
ferritic (plain chromium stainless category) stainless steel,
offering general-purpose corrosion resistance, often in decorative
Statistical Process Control (SPC)
A technique used to predict when a steelmaking function's
quality may deteriorate. By tightly monitoring the product's
variance from specifications, the operator can determine when
to apply preventative maintenance to a machine before any
low-quality (secondary) steel is produced.
A reversing steel sheet reduction mill with heated coil boxes
at each end. Steel sheet or plate is sent through the rolls
of the reversing mill and coiled at the end of the mill, reheated
in the coil box, and sent back through the Steckel stands
and recoiled. By reheating the steel prior to each pass, the
rolls can squeeze the steel thinner per pass and impart a
better surface finish.
The amount of steel used per unit of gross domestic product.
Intensity reflects the secular demand for steel, as opposed
to cyclical demand. The amount of steel used in vehicles and
the popularity of alternative materials affect the intensity,
or how much steel is needed per unit produced. The state of
the economy, however, determines the number of units.
Consumer products such as automobiles and appliances that,
because so much of their weight is from steel, exhibit a high
demand correlation with steel.
Steel Service Center Inventories
End-of-period material stocks reported by the Steel Service
Center Institute (SSCI).
Banding and packaging material that is used to close and reinforce
shipping units, such as bales, boxes, cartons, coils, crates,
Properties related to the ability of steel to oppose applied
forces. Forms of strength include withstanding imposed loads
without a permanent change in shape or structure and resistance
Stress Corrosion Cracking (SCC)
Slow growth of cracks in stainless steel caused by the combined
effect of mechanical stress and exposure to a corrosive environment.
Thin, flat steel that resembles hot-rolled sheet, but it is
normally narrower (up to 12 inches wide) and produced to more
closely controlled thicknesses. Strip also may be cut from
steel sheet by a slitting machine (see Sheet Steel).
Steel product group that includes I-beams, H-beams, wide-flange
beams and sheet piling. These products are used in the construction
of multi-story buildings, industrial buildings, bridge trusses,
vertical highway supports, and riverbank reinforcement.
Raw material used as an input for steel processing: For example,
hot-rolled steel is the substrate for cold-rolling operations.